PWM? K. A. Connor Mobile Studio Project Center for Mobile Hands-On STEM SMART LIGHTING Engineering Research Center ECSE Department Rensselaer Polytechnic Institute

Outline Overview Outcomes Activities Tasks Materials & Supplies References/Resources Nomenclature Questions 18 September 201818 September 2018

Overview Take light apart and put it back together Observe the colors from standard ‘white’ light bulbs using a diffraction grating Observe the pixel colors in LCD display using magnifying lens or microscope Generate at least 3 colors of light using LEDs Use color mixing app or program to show possibilities & importance of amount of each color Use PWM to control intensity of light Use 3 PWM systems to control relative intensity of red, green, blue & white (other colors too) 18 September 201818 September 2018

Tasks Participants will Identify activities, concepts, etc. appropriate for 5th grade students Identify STEM related outcomes that can be addressed using activities, concepts, etc. Develop outreach activities for 5th grade students. 18 September 201818 September 2018

Diffraction Grating Set up three clamp on lamps with incandescent, CFL & LED bulbs Observe color spectra using diffraction grating slide Technique Observations Describe (Draw?) the similarities & differences in the light observed from the three bulbs 18 September 201818 September 2018

Spectra 18 September 201818 September 2018

What do Humans See? 18 September 201818 September 2018

Magnifying Lens Observe RGB color pixels in LCD using a magnifying lens (microscope) 18 September 201818 September 2018

Stickie Light a series of LEDs using a CR2032 coin battery (red, green, blue, white, yellow, orange …) Try each in turn – note polarity Try two or more at once – conclusions? Complete Stickie Attach LED to battery with tape Add strong magnet to coin Attach with tape See where it sticks 18 September 201818 September 2018

Mobile Studio Frequency Control – set from 1Hz to 1kHz Duty Cycle – set from 0% to 100% Output voltage range: off is 0V and on is 3.3V (uses digital levels) 18 September 201818 September 2018

Mobile Studio Plug in Mobile Studio Connect PWM1 and digital GND to 10Ω resistor in series with LED Turn on PWM software Select 1Hz and 50% duty cycle Try different frequencies and duty cycles Select 120Hz (frequency of most common bulbs) and vary duty cycle from 0% to 100% Observe average voltage with DC voltmeter What is PWM? 0.1Hz and then count seconds for each duty cycle? 18 September 201818 September 2018

Analog Discovery Frequency Control – set from 0 to 10 times 10A where A is power of 10 Duty Cycle – set from 0% to 100% Start – to begin Output voltage range: off is 0V and on is 3.3V; voltage is 1.65V when Start is not selected 18 September 201818 September 2018

Analog Discovery Plug in Digilent Analog Discovery Connect Yellow (AWG1) and Black (GND) wires to 10Ω resistor in series with LED Turn on ADAP software and select PWM Select 1Hz and 50% duty cycle and start Try different frequencies and duty cycles Select 120Hz (frequency of most common bulbs) and vary duty cycle from 0% to 100% Observe average voltage with DC voltmeter What is PWM? 0.1Hz and then count seconds for each duty cycle? 18 September 201818 September 2018

RGB Light Bulb Install RGB bulb with remote Explore controls Observe light 18 September 201818 September 2018

RGB PWM Combine three LED Mobile Studio or Analog Discovery Setups Each group controls a color in the 3 color LED Explore how to make white light of different intensities 18 September 201818 September 2018

BOM? Bill of Materials Diffraction grating slide Magnifying glass or microscope Incandescent, CFL, LED bulbs with clamp on lamps Bright LEDs (Red, Green, Blue, Yellow, Orange, White … separately and in RGB package) CR2032 Coin Batteries ¼” Neodymium Iron Boron Magnets Analog Discovery or Mobile Studio Resistors (10Ω, 100Ω, 500Ω, 1kΩ) Protoboard & jumper wires Three color bulb with remote, LED touch lamp Solar cell Inexpensive multi-meter BOM? 18 September 201818 September 2018

References/Resources http://en.wikipedia.org/wiki/RGB_color_model http://arduino.cc/en/Tutorial/PWM http://led.linear1.org/1led.wiz or http://www.instructables.com/id/Choosing-The-Resistor-To-Use-With-LEDs/ http://electronicsclub.info/leds.htm 18 September 201818 September 2018

Nomenclature PWM LED Diffraction Voltage Current Resistance Pixel RGB LCD CFL Incandescent Neodymium Iron Boron Magnets Solar Cell Multi-meter 18 September 201818 September 2018

New Visions Outreach Goals/Outcomes Content Level … 18 September 201818 September 2018

Questions Start with separating colors from light bulbs and possibly LCD monitors, using diffraction slides Divide colors and show one can make white from RGB or something. Measure average with DC voltmeter Eveready desk lamp PWM Lights and motors? AD Board cannot drive motor. High efficiency LED operation – pick the correct resistor. 5x5 array of 3 color LEDs, driven by audio amps. Takes about 5W each. Maybe 4x4 with 5x5 white LEDs to give flexibility Small box to be ‘stage’ or office or something Do stickies to show how to make colors with LEDs Show how levels of each color can be controlled on average. Compare with commercial bulb. 18 September 201818 September 2018